In recent years, to improve the paint color development speed of an automobile company, a paint-design support tool using a computer has been developed in various fields. For example, to improve the design effect, there is a metallic paint color obtained by mixing a chromatic pigment and a flaky effective pigment (aluminum flake or pearl flake) or micro titanium oxide using Rayleigh scattering in a binder. Because the brightness, chroma, and hue are changed depending on a seeing angle, appearance such as metallic sense and pearl sense is felt.
As a conventional method for developing these paint colors, a method is generally used in which a designer, referred to as a color stylist, of an automobile company orally describes desired appearances of cloth, a cosmetic bottle, a shell, and an image in a magazine to a toning designer of a paint company to ask the designer about the development of paint colors, and this communication is in the main stream also at present. Because this method depends on an individual experiment and expression ability, non-efficiency, because a paint color which does not satisfy an order can be prepared, is regarded as a problem due to a difference between the opinions of a color stylist, who is an orderer of colors, and a toning designer.
However, emblematic of the IT revolution, because the performance of equipment for measuring a color, computers, and display monitors are improved, performing paint color design using a computer is a need of the time in automobile and paint companies. By using this equipment, it is possible to expect improvement in the accuracy of and speedup of paint color development.
The present invention provides an algorithm and procedure of a computer system for optionally changing the appearance of a metallic paint color including flake pigments having many colors on a screen and displaying a new color on the screen.
When designing a new design on a screen, a new color is not prepared from completely nothing. In general, a method has been used so far in which a color (this is referred to as a modified color) is obtained by correcting and changing a paint color (this is referred to as an original color) that has been prepared in the past that goes in the preferred direction.
Therefore, an algorithm and procedure for actually preparing a modified color are finished as a system by measuring a metallic paint color which is an original color by a goniospectrophotometric calorimeter, changing a reflectance at every angle such as the whole receiving angle, highlight, front, or shade, thereby changing a color and appearance to prepare a new color, converting the prepared color into RGB and displaying the original color and modified color on a screen as full color graphic to visually determine the appearance, using a decided spectral reflectance and thereby searching an approximate color from a database for existing paint colors to obtain a past formulation, and obtaining an estimated formulation in accordance with metallic CCMS. A system is provided which is able to compute a multi-angle spectral reflectance, prepare a computer graphic in accordance with a reflectance in which a color and appearance are optionally changed, display images of the original color and modified color at the same time and visually evaluate them, search an approximate color in accordance with the paint color database, or calculate a formulation in accordance with CCM.
A metallic color is measured by a large goniospectrophotometric colorimeter (GCMS made by Murakami Color Research Laboratory) to calculate an appearance parameter in accordance with a goniospectrophotometric reflectance. There is a computer graphic apparatus having means for calculating first=depending on a spectral wavelength and second=depending on a receiving angle and estimating a spectral reflectance in which appearance is changed (refer to Japanese Patent Application Publication No. 123981/1996). Though the goniospectrophotometric colorimeter used for this method is precise because measurement can be made every degree, it has a disadvantage that measurement requires a lot of time. Moreover, it is necessary to calculate two characteristic parameters by previously computing many goniospectrophotometric reflectances.
There is a method for mapping a measured value every degree into an angle of an automobile shape by the large goniospectrophotmetric colorimeter (GCMS made by Murakami Color Research Laboratory), displaying it by a commercial photograph editing software, and masking it to correct a color (refer to Japanese Patent Application Laid-Open No. 222653/1998). In this case, the original color has a color-measured reflectance. However, a modified color has RGB values to be processed by the photograph editing software but it cannot be obtained from a spectral reflectance. Moreover, because a corresponding relation between the receiving angle of the modified color and the color cannot be clarified, it is impossible to search the modified color from a paint-color database or perform CCM in accordance with a reflectance.
There is a method for preparing a real photograph by mapping it into the spectral reflectance of a paint color and the three-dimensional shape of an automobile shape and rendering it while including environmental light to evaluate an outer plate color of an automobile (refer to Japanese Patent Application Laid-Open No. 66119/1999). However, this is a method for mapping an existing paint color into a three-dimensional shape. It does not chromatically change an original color or prepare a new color.
There is a method for converting the RGB of a CG (simulation image or digital camera image) into XYZ and searching an approximate color from a database by using a fuzzy inference and considering the ambiguity of a person (refer to Japanese Patent Application Laid-Open No. 269411/1999). This method does not prepare a modified color from the spectral reflectance of a measured color value.
By using a sample book database (including paint formulation), the goniospectrophotometric color measured value in the database, and the three-dimensional data for an automobile, a CG of the automobile is prepared by rendering the modified color measured value and the three-dimensional data at a high speed. Moreover, a color is set so that a designer can select a paint color in accordance with a design term by linking with sensibility information (refer to Japanese Patent Application Laid-Open No. 66119/1999). This is retrieval of a sensibility database but it is not a modified color.
There are a color conversion method for converting the original color of an original image into a modified color and a method for rendering an automobile into a color seen under external light by using the database of the characteristic data for original colors (Japanese Patent Application Laid-Open No. 232430/1999: Object-image color modification method). However, this is a method for changing colors in accordance with the same technique as that shown in Japanese Patent Application Laid-Open No. 123981/1996 and has the disadvantage that two characteristic parameters must be calculated by previously computing many goniospectrophotometric reflectances.
Therefore, it is an object of the present invention to provide a design tool capable of developing a new paint color, particularly determining the quality of a design by computing a reflectance without greatly deteriorating the characteristic of a spectral reflectance obtained from a multi-angle spectrophotometer of original colors, slightly correcting colors, calculating the spectral reflectance of a new modified color, using the spectral reflectance as a computer graphic and thereby simultaneously displaying images before and after being changed on a monitor, and visually determining a color correction direction.
It is another object of the present invention to provide a paint-color design tool for an industrial purpose of displaying a message showing whether the determination showing whether a modified color after being changed can be realized in a desired painting process (for example, multi-layer coating such as 2C1B or 3-coat), and the application line of a targeted automobile company is industrially effected by collating the determination with the limit value of preset color reproduction.
It is still another object of the present invention to provide an approximate color retrieval tool for new design development for searching approximate colors at multi-angles from an existing paint-color database by using a changed spectral reflectance and searching a most approximate color and a color having an appearance and quickly preparing a modified color in accordance with the paint color of a retrieval result.
It is still another object of the present invention to provide color-designing metallic CCM for quickly preparing a modified color by using the spectral reflectance of a modified color and thereby performing metallic CCM in accordance with the above approximate color retrieval when there is no approximate color and calculating a formulation of color materials through calculation.